Materials that may not burn in room air can ignite easily and burn fiercely in an oxygen-enriched environment (a situation when the concentration of oxygen is greater than in ordinary room air). In fact, most surgical fires occur in an oxygen-enriched environment.

Other factors also increase the risk of fire. For example, alcohol-based skin preparation agents are very flammable when still wet. The placement of surgical drapes (such as when they are placed in a way that allows oxygen to pool under them), and the handling of ignition sources (such as resting hot ignition sources on the drapes) may also increase the chance that a surgical fire will occur.

Fires burn hotter and faster in an oxygen enriched environment. The image above shows a nasal cannula set on fire in room air (left) and in an oxygen enriched environment (right). Courtesy of Anesthesia Patient Safety Foundation.